There currently is a real need for a long term and objective alcohol biomarker to both monitor alcohol-impaired healthcare professionals, and to aid in the selection of organ transplant recipients, particularly liver transplant recipients. We recently concluded a Phase I study that compared the presence of the direct alcohol biomarker ethyl glucuronide (EtG) in hair samples from non-drinkers to hair samples obtained from problem drinkers (hair was chosen because of its 3-month exposure window to various drugs). As an alcohol biomarker EtG distinguished the drinkers from the non-drinkers with a sensitivity of 80% and a specificity approaching 100%. To determine the utility of EtG in hair and fingernail clippings as a long-term alcohol biomarker we are proposing a Phase II study that will involve two distinct population groups. One population group will consist of college students (approximately 600) that represent a span of drinking behaviors from little or no drinking to heavy and binge drinking. From this population we will determine the dose response of alcohol consumed to the amount of EtG found in the hair and fingernails. Extent of alcohol consumption by student volunteers will be determined using the technique of timeline followback interviews. The second population group studied will consist of impaired health care professionals suffering from alcohol abuse who are entering an alcohol treatment center and who will be sequestered from alcohol during treatment. From this population we will determine the half-time of the "washout" rate of EtG under normal hair washing and treating conditions. Hair and fingernail samples will be obtained from the volunteers at admittance, half-way through the treatment program, and upon release from the treatment program. From these samples an average half-life of EtG in hair and fingernails will be determined and from these data an average window of detection of EtG in hair and fingernails will be extrapolated. The data obtained in this Phase II study will establish the parameters of the presence of EtG in hair and fingernail samples, and will validate the conditions by which EtG in hair and/or fingernails can be used to either monitor alcohol-impaired healthcare professionals or aid in the selection of organ transplant recipients. PUBLIC HEALTH RELEVANCE: There is an immediate need for an objective means of determining alcohol ingestion by two population groups: 1) alcohol-impaired healthcare professionals undergoing treatment while continuing to practice their profession, and 2) potential organ transplant recipients, particularly liver transplant recipients. The presence of the direct alcohol biomarker ethyl glucuronide in hair and/or fingernail clippings has considerable potential as a means of objectively monitoring alcohol ingestion by these two groups and facilitating their management.